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Saturday, June 6, 2015

Update on copper coils

I do a few weird projects now and then. Folks might want an update on how they are working out. Here's a couple reasons why I buy copper rolls by the box.

This a pretty common use for a copper coil. This coil is wrapped around the stovepipe of my woodstove. On the other other side of the wall is a standard 40 gallon electric water tank. The coil is connect to the bottom and then the top of the water tank. That allows normal convection currents to transfer heat from the woodstove to the water tank. It wasn't getting quite hot enough for my liking so I added a second coil directly behind the firebox that then fed into the stovepipe coil.

The electric elements in the water tank are still fully functional. However, the tank is on a switch so I can turn them off. That saves a huge amount of electricity. The woodstove alone raises the freezing cold well water to about 100F. A short boost from the electric elements brings the water to 120F. Standard electric hot water tanks are normally a big part of a home's electric usage.

Another power hog is the regular electric refrigerator -especially if it's a number of years old, like mine. Unlike other refrigerators this one has a huge copper coil in the middle of it. Every drop of ice cold water used in my house first travels through the refrigerator coil. It's so effective that I can unplug the refrigerator and food keeps just fine. However, I still want to use freezer so the unit is plugged into the grid. In spite of that the coil appears to be greatly reducing power usage. Should the grid go down, my well pump is powered by my solar electric system so I'd still have refrigeration. That system was actually tested for over month with no grid power. Worked fine.

My Home has a moderately sized solar electric system. Still, I've decided to keep the grid rather than run a backup generator. It does allow me to be lazy. For example on warm days I'll often use electricity to cook with. I do have an outdoor propane stove, but bad weather and bugs drive me back inside. Another big power draw is electric power tools. Sure I could do all those jobs with hand tools, but there are only so many hours in the day. Many of them I like to spend fishing instead of doing things like hand sanding.

Keep in mind that New Hampshire has some of the highest electric rates in the country. In spite of that my last electric bill was $40. Only half the bill is actual electric usage. The other half is delivery fees. It would be a whole lot higher without the magic of my copper coils.



  1. Nice cooling and heating set up. Did you have to sand pack the copper to coil it that tight? All I have done with copper tubing has been to make a condenser for boiled beer to be rendered to it purest form.

    1. No sand. Clamped a piece of stovepipe in a vise and was careful to wrap the coil really tight. Takes a steady hand to do it that way.

      Ah yes, "Backpacker Beer" Most of the water taken out to save weight. :)

  2. I'm tellin' ya, you are an inspiration.
    If I had my own house, the first thing I would do would be to drag the huge wood cookstove I have had in storage for 25 years out and put a coil around it like that.
    The refrigerator coil is just brilliance though.
    Fortunately one nice thing about the Pacific Northwest is the cheap electricity compared to other parts of the country, Hydroelectric baby, it's the way to go.
    Not that I will ever see a measly forty dollar electric bill in my lifetime.

    1. I love those old stoves. Many of them were built to take a coil right inside the firebox.

      I was going to put the coil in a big cooler, but my lovely wife suggested I go right to our kitchen fridge. Not many wives would put up with that sort of thing, never mind suggest it.

  3. Sounds like the wife is totally on board with the different way of doing things. What a great partner!

  4. Folks could save a lot of money if they'd just put up with a TINY bit of inconvenience and effort.

  5. My family lives on a ranch in the countryside and we try, as much as possible to stay off the grid. Copper tubing/coils are great for all sorts of things like this! Heating water on a wood stove worked for a lot of things, but our shower was freezing in winter until we ran a copper coil to the water tank!